Method for winding brushless dc motors

ABSTRACT

A method of making a wound field for a brushless direct current motor, direct current generator, alternating current motor or alternating current generator, includes steps of providing a base mold and a press mold. Another step comprises determining a number of phases. At least one strand of conductive material per phase is formed between the base mold and press mold into a conductive coil that has a shape that indicates the number of poles required. Each conductive coil is inserted into the stator core, and the stator core is installed into one of a brushless direct current motor, direct current generator, alternating current motor or alternating current generator.

BACKGROUND OF THE PRESENT INVENTION

This application is a divisional of application Ser. No. 11/695,955,filed Apr. 3, 2007, entitled METHOD FOR WINDING BRUSHLESS DC MOTORS, theentire contents of which are incorporated herein by reference.

The present invention relates to a method for making a winding for amotor or generator, and more specifically, a method for making a windingfor an AC or DC brushless motor or generator.

Slotless brushless DC motors are known for having performance advantagesas compared to traditional motors and are used in many capacities frommedical equipment to pumps. Conventional methods are to wind a separatecoil or group of coils for each magnetic pole required. The lack ofdefined slots and teeth, however, make the winding process moredifficult and expensive than typical brushless DC motors that includeteeth and slots.

Accordingly, a simplified winding method that requires only one coil perphase no matter how many poles are present in the motor is desired.

SUMMARY OF THE INVENTION

In one aspect of the present invention, a method of making a wound fieldfor a brushless direct current motor, direct current generator,alternating current motor or alternating current generator, includesproviding a base mold having an engagement face and at least one movableend turn form on the engagement face. A number of distinct phases isdetermined and at least one strand of conductive material is woundaround at least one movable end turn forming tool per distinct phase. Aconductive coil is created from each strand of conductive material foreach distinct phase. Each conductive coil is formed into a configurationthat indicates the number of poles required. Each conductive coil isthen placed onto an insertion instrument. Each of the aforementionedsteps is repeated as necessary to create a conductive coil for eachdistinct phase. The insertion instrument and each conductive coil areinserted into a stator core. The insertion instrument is removed fromthe stator core, and the stator core is installed into one of abrushless direct current motor, direct current generator, alternatingcurrent motor or alternating current generator.

These and other features, advantages and objects of the presentinvention will be further understood and appreciated by those skilled inthe art upon studying the following specification, claims, and appendeddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of a base mold and a press mold usedfor making a two-pole coil configuration;

FIG. 1A is a bottom perspective view of the press mold of FIG. 1;

FIG. 1B is a top elevational view of the base mold of FIG. 1;

FIG. 2 is a front perspective view of the base mold and press mold ofFIG. 1, with the end turn forms removed;

FIG. 3 is a front perspective view of the base mold and press mold ofFIG. 1 during formation of a conductive coil;

FIG. 4 is a front perspective view of the press mold and base mold ofFIG. 1, after the conductive coil has been formed;

FIG. 5 is a front perspective view of a coil configuration for atwo-pole motor or generator;

FIG. 6A is a front perspective view of another embodiment of a base moldand a press mold for a four-pole coil configuration following winding ofa conductive material;

FIG. 6B is a side elevational view of the base mold and press mold ofFIG. 6A;

FIG. 6C is a top elevational view of the base mold and press mold ofFIG. 6A;

FIG. 7 is a front perspective view of the base mold and press mold ofFIG. 6 during formation of a conductive coil;

FIG. 8 is a front perspective view of a conductive coil configurationfor a four-pole motor or generator;

FIG. 9 is a front perspective view of another embodiment of a base moldand a press mold for a six-pole coil configuration following winding ofa conductive material;

FIG. 9A is a top elevational view of the base mold of FIG. 9;

FIG. 10 is a front perspective view of the base mold and press mold ofFIG. 9 during formation of a conductive coil, with a portion of thepress mold broken away;

FIG. 11 is a front perspective view of a coil configuration for asix-pole motor or generator;

FIG. 12 is a front perspective view of one embodiment of an insertioninstrument of the present invention;

FIG. 13 is a front perspective view of the insertion instrument of FIG.12 engaged with conductive coils prior to insertion into a stator core;

FIG. 14 is a front perspective view of the insertion instrument of FIG.12 engaged with a conductive coil during insertion of the conductivecoil into the stator core;

FIG. 15 is a front perspective view of the insertion instrument of FIG.12 engaged with a conductive coil after complete insertion of theconductive coil into the stator core;

FIG. 16 is a front perspective view of the conductive coil fullyinserted into the stator core;

FIG. 17 is a front perspective view of a molded insulator for a statorcore;

FIG. 18 is a front perspective view of a conductive coil inserted into amolded insulator; and

FIG. 19 is a front perspective view of a conductive coil and moldedinsulator inserted into a stator core.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

For purposes of description herein the terms “upper”, “lower”, “right”,“left”, “rear”, “front”, “vertical”, “horizontal” and derivativesthereof shall relate to the invention as oriented in FIGS. 1-5. However,it is to be understood that the invention may assume various alternativeorientations and step sequences, except where expressly specified to thecontrary. It is also to be understood that the specific devices andprocesses illustrated in the attached drawings, and described in thefollowing specification are simply exemplary embodiments of theinventive concepts defined in the appended claims. Hence, specificdimensions and other physical characteristics relating to theembodiments disclosed herein are not to be considered as limiting,unless the claims expressly state otherwise.

Referring to FIGS. 1-5, the reference numeral 8 generally designates amolding system having a base mold 10 with first and second end turnforms 12, 14. The first and second end turn forms 12, 14 are adapted tobe inserted into first and second slots 16, 18 (FIG. 2) that openupwardly on an engagement face 20 of the base mold 10. The end turnforms 12, 14 are used to make a wound coil 22 for a brushless directcurrent motor, direct current generator, alternating current motor oralternating current generator. The wound coil 22 is made from aconductive material 25 wound about the first and second end turn forms12, 14 to create one loop of conductive material. After winding iscomplete, the end turn forms 12, 14 may be removed from the base mold10. A press mold 24 is provided having an application face 26 that iscomplementary in shape to the engagement face 20 of the base mold 10.The press mold 24 may have downwardly extending slots adapted to receivethe end turn forms 12 and 14. The one loop of conductive material 25 isformed between the application face 26 of the press mold 24 and theengagement face 20 of the base mold 10 to provide a formed coil 30 ofconductive material. The formed coil 30 is removed from the engagementface 20 of the base mold 10. The formed coil 30 is slid over aninsertion instrument 32 (FIG. 12). The insertion instrument 32 and theformed coil 30 are forced into a cylindrically-shaped stator core 34(FIG. 19). Optionally, the formed coil 30 may be bonded by a varnish oradhesive. The insertion instrument 32 is removed from the stator core34, and the stator core 34 is installed into one of a brushless directcurrent motor, direct current generator, alternating current motor oralternating current generator.

Referring again to FIGS. 1-4, the engagement face 20 of the base mold 10is generally convex, with the center of the base mold having a heightgreater than first and second sides 38, 40 of the base mold 10. However,it is contemplated that other engagement face arrangements are possible.As shown in FIG. 1B, the first and second end turn forms 12, 14 have agenerally concave side 42 and a generally convex side 44 wherein theconcave sides 42 of both the first and second end turn forms 12, 14 faceinwardly toward the center of the base mold 10. The application face 26of the press mold 24 has a concave construction such that the center ofthe press mold has a depth less than the first and second sides 46, 48of the press mold 24. However, it is contemplated that other applicationface arrangements are possible.

To prepare a two-pole coil for installation into the stator core for usein a brushless direct current motor, direct current generator,alternating current motor or alternating current generator, the firstand second end turn forms 12, 14 are inserted into the first and secondslots 16, 18, respectively, of the base mold 10. At least one strand ofconductive material 25 is then wound about the ends and the convex side42 of the first and second end turn forms 12, 14. The distance D1between the end turn forms 12, 14 is equal to the height, or stacklength, of the conductive coil 22 after the conductive coil 22 has beenformed and installed into the stator core 34 plus room for clearance.The clearance refers to minimal spacing associated with the thickness ofthe conductive coil 22. After a predetermined number of revolutions hasbeen made around the end turn forms 12, 14 and a conductive coil 22 hasbeen made, the conductive material is cut. The end turn forms 12, 14 maybe removed from the first and second slots 16, 18. Alternatively, theend turn forms 12, 14 may retract into first and second slots 16, 18.The end turn forms 12, 14 may be spring biased to an extended positionand pressed into the first and second slots 16, 18 by the applicationface 26 of the press mold 24. The application face 26 of the press mold24 is designed to descend upon and engage the engagement face 20 of thebase mold 10 to shape the three dimensional formed conductive coil 30.The press mold 24 is lifted and the formed conductive coil 30 is removedfrom the base mold 10. Optionally, the formed coil 30 may be bonded by avarnish or adhesive. The formed conductive coil 30 for a two-pole motoror generator has two stack portions 50 and two end turn portions 52.

Referring now to FIGS. 6A, 6B, 6C, 7, and 8, to prepare a four-pole coilfor installation into a stator core used in a brushless direct currentmotor, direct current generator, alternating current motor oralternating current generator, first and second end turn forms 60, 62are inserted into first and second slots 64, 68, (FIG. 7) respectively,of first and second upwardly extending columns 70, 72, respectively, onan engagement face 73 of a base mold 74. Each upstanding column 70, 72has a rectangular winding contour 75 adjacent to a slanted formingcontour 76. The first and second slots 64, 68 are disposed in therectangular winding contour 75 of the first and second upwardlyextending columns 70, 72, respectively. At least one strand ofconductive material 78 is then wound around the ends and a convex side80 of each of the first and second end turn forms 60, 62. After apredetermined number of revolutions has been made around the end turnforms 60, 62 and a conductive coil 82 having a rectangle-like shape hasbeen made, the conductive material 78 is cut. The distance D2 betweenthe end turn forms 60, 62 is approximately equal to two times the stacklength plus the pole pitch plus clearance. The end turn forms 60, 62 arethen removed from the first and second slots 64, 68 in the rectangularwinding contours 75 of the first and second upwardly extending columns70, 72. Alternatively, the end turn forms 60, 62 may retract into thefirst and second slots 64, 68. The end turn forms 12, 14 may be springbiased to an extended position and pressed into the first and secondslots 64, 68 by the application face 84 of the press mold 86. Anapplication face 84 of a press mold 86 engages the engagement face 73 ofthe base mold 74 to make a three dimensional formed conductive coil 90.More specifically, two ridges 92 on the application face 84 contact theconductive coil 82 on two sides of the coil, thereby forcing the middleportion of the conductive coil 82 downwardly toward a bottom of the basemold 74. As the conductive coil 82 is formed, the ends of the conductivecoil 82 slide off the rectangular winding contour 75 of the first andsecond upwardly extending columns 70, 72 and onto the slanted formingcontours 76. The width W1, shown in FIG. 6C, of the slanted formingcontours 76 is approximately equal to the width W2 of the end turn forms60, 62 which is equal to the pole pitch present in the motor orgenerator being constructed. The height from the lowest side of theslanted forming contour to a bottom 94 of the base form is equal to thestack length of the formed conductive coil 90. When the application face84 contacts a bottom of the base form 74, the formed conductive coil 90is complete. The press mold 86 is lifted and the formed conductive coil90 is removed from the base mold 74. Optionally, the formed conductivecoil 90 may be bonded by a varnish or adhesive.

The conductive coil, shown in FIG. 8, for a four-pole motor or generatorincludes four stack portions 100 and four end turn portions 102. As willbe described in greater detail below, for each number of poles requiredfor a particular motor or generator, the number of stack portions andend turn portions will be equal to the number of poles present.

As shown in FIGS. 9-11, to prepare a six pole coil for installation intothe stator for use in a brushless direct current motor, direct currentgenerator, alternating current motor or alternating current generator,first, second, and third end turn forms 110, 112, 114 are inserted intofirst, second, and third slots 116, 118, 120, respectively, present infirst, second and third upwardly extending columns 122, 124, 126,respectively, of a base mold 130. Each upstanding column 122, 124, 126has a rectangular winding contour 132 adjacent to a slanted formingcontour 134. The first, second, and third slots 116, 118, 120 aredisposed in the rectangular winding contour 132 of the first, second andthird upwardly extending columns 122, 124, 126, respectively. At leastone strand of conductive material 136 is then wound about the first,second, and third end turn forms 110, 112, 114 so that the conductivematerial 136 wraps around a convex side 140 of each end turn form 110,112, 114. The distance D3 between the end turn forms 110, 112, 114 isapproximately equal to two times the stack length plus the pole pitchplus clearance. After a predetermined number of revolutions have beenmade around the end turn forms 110, 112, 114 and a conductive coil 142having a triangle-like shape has been made, the conductive material 136is cut. The end turn forms 110, 112, 114 are then removed from thefirst, second, and third slots 116, 118, 120, respectively, in thewinding contour 132 of the first, second and third upwardly extendingcolumns 122, 124, 126, respectively. Alternatively, the end turn forms110, 112, 114 may retract into the first, second and third slots 116,118, 120. The end turn forms 110, 112, 114 may be spring biased to anextended position and pressed into the first, second, and third slots116, 118, 120 by the application face 144 of the press mold 146. Anapplication face 144 of a press mold 146 then engages an engagement face148 of the base mold 130 to form a three dimensional formed conductivecoil configuration 150 (FIG. 11). More specifically, the applicationface 144 includes three ridges 152 adapted to contact the conductivematerial 136 on each of three sides of the conductive material 136, andforce the conductive material 136 downwardly toward the base of theupwardly extending columns 122, 124, 126. As the formed conductive coil150 is made, the ends of the formed conductive coil 150 slide off therectangular winding contour 132 and onto the slanted forming contours134. The width W1 of the slanted forming contour 134 is approximatelyequal to the width W2 of the end turn forms 110, 112, 114 which is equalto the pole pitch that will be present in the motor or generator beingconstructed. The height from the lowest side of the slanted formingcontours 134 to the engagement face 148 of the base form 130 may beequal to or more than the stack length. Optionally, the formedconductive coil 136 may be bonded by a varnish or adhesive. When theridges 152 contact the engagement face 148 of the base form 130, theconductive coil 136 is fully formed. The press mold 146 is lifted andthe formed conductive coil 150 is removed from the base mold 130.

The formed conductive coil 150 for a six-pole motor or generator, asshown in FIG. 11, includes six stack portions 160 and six end turnportions 162. The embodiments disclosed above are for illustration andit is contemplated that eight, ten, twelve, etc. pole motors orgenerators can be constructed in a similar manner as described abovewith respect to the two, four and six pole coil wind and formoperations. For an eight, ten, twelve, etc. pole motor or generator, theconductive coil will have the same number of stack portions and end turnportions as the number of poles in the motor or generator. More coilsmay be appropriate if more phases are used in the motor or generator.

Referring now to FIGS. 12-16, the insertion instrument 32 includes aconical front piece 172, an elongate body 174, a stop plate 176, and aplunger 178. Optionally, protrusions 175 may extend along the elongatebody and provide some separation between multiple conductive coilsarranged on the insertion instrument 32. The blades may be angled orextend parallel with the longitudinal extent of the insertioninstrument, as shown in FIG. 12. The tapered construction of the conicalfront piece 172 allows the insertion instrument 32 to be insertedbetween one or more conductive coils 180, as shown in FIG. 13. Theoutside diameter of the insertion instrument 32 is designed to form andthen size an inside diameter 179 (FIG. 16) of the coils 180 to fitwithin an inside diameter of the stator core 34. More specifically, theinsertion instrument 32 has an outside diameter that is sized to shapean inside diameter 179 of a/many coil(s) 180 during insertion of thecoil(s) 180 into the stator core 34, regardless of the number of stackportions and end turn portions on the coil(s) 180. The coils 180 areshown in FIG. 13 having a shape similar to those in FIG. 5, but includerounded corners. In addition, The insertion instrument may be used tohold the conductive coils 180 while the coils 180 are being varnished orbonded. The insertion instrument 32 may include at least one hook 182and may include several hooks 182 designed to contact and hold a portionof the conductive coil 180 prior to the conductive coil 180 being fullyinserted into the stator core 34. The hooks 182 are connected inside theelongate body 174 to the plunger 178. Alternatively, there may be hooks182 on the elongate body 174 near the stop plate 176. When the plunger178 is depressed, the hooks 182 retract into recesses 186 in the conicalfront piece 172. In an alternative embodiment, the hooks 182 retractinto the elongate body 174. When the insertion instrument 32 has beeninserted into the stator core 34 a predetermined distance, as shown inFIG. 14, the plunger 178 is depressed and the hooks 182 are retracted toallow the conductive coil 180 to slide back along the elongate body 174of the insertion instrument 32 as shown in FIG. 15. Once the conductivecoil 180 has been properly positioned inside the stator core 34, theinsertion instrument 32 is withdrawn from contact with the conductivecoil 182, leaving the conductive coil 182 in contact with an insidediameter of the stator core 34 (FIG. 16).

As shown in FIGS. 17-19, an insulator may be present inside the statorcore 34. A variety of different insulators may be used, including asheet film insulator, powder insulator, molded insulator or any otherinsulator that is relatively nonconductive. If a sheet film insulator isused, the sheet film insulator is wrapped about the inside diameter ofthe stator core 34. If a powder insulator is used, the stator core 34may be electrically charged by a charging tool, and the powder issprayed onto the stator core 34. The powder is then wiped off of theoutside diameter of the stator core 34 and allowed to remain on theinside of the stator core. The powder is then heated and cured to ensurethat the powder provides a nonconductive solid coating that stays on thestator core 34. Alternatively, the stator core 34 could be dipped in afluidized bed of powder and cured. If a molded insulator 190, as shownin FIG. 17, is used, the molded insulator 190 is typically shaped to beclosely received in the stator core 34 and includes circumferentialflanges 188 adapted to hold the molded insulator 190 in place inside thestator core 34. The molded insulator 190 may include protrusions 192that help hold the conductive coil 180 in place inside the moldedinsulator 190. The molded insulator 190 is then inserted into the statorcore 34. After the molded insulator 190 is inserted into the stator core34, the conductive coil 180 is forced into the molded insulator 190 bythe insertion instrument 32, as described above. Alternatively, theconductive coil 180 may be inserted into the molded insulator 190 firstby the insertion instrument 32. Then the molded insulator 190 andconductive coil 180 together are inserted into the stator core 34 by theinsertion instrument. The stator core 34 is then ready to be insertedinto a motor or generator.

The above description is considered that of the preferred embodimentsonly. Modifications of the invention will occur to those skilled in theart and to those who make or use the invention. Therefore, it isunderstood that the embodiments shown in the drawings and describedabove is merely for illustrative purposes and not intended to limit thescope of the invention, which is defined by the following claims asinterpreted according to the principles of patent law, including theDoctrine of Equivalents.

1. A method of making a wound field for a brushless direct currentmotor, direct current generator, alternating current motor oralternating current generator, said method comprising the steps of: (a)providing a base mold having an engagement face and at least one movableend turn form on the engagement face; (b) determining a number ofdistinct phases; (c) winding at least one strand of conductive materialper distinct phase around at least one movable end turn forming tool;(d) creating a coil of conductive material from the at least one strandof conductive material; (e) forming the coil into a shape that indicatesthe number of poles required; (f) placing the coil onto an insertioninstrument; (g) repeating steps (b) through (f) as needed to create acoil for each distinct phase; (h) inserting the insertion instrument andeach coil into a stator core; (i) sizing an inside diameter of thecoil(s) with the insertion instrument; (j) removing the insertioninstrument from the stator core; and (k) installing the stator core intoone of a brushless direct current motor, direct current generator,alternating current motor or alternating current generator.
 2. Themethod of claim 1, further comprising the step of: inserting a moldedinsulator into the stator core in abutting contact with the insidediameter of the stator core.
 3. The method of claim 2, furthercomprising the step of: inserting the formed coil into an insidediameter of the molded insulator.
 4. The method of claim 1, wherein thestator core includes a molded insulator and wherein the formed coil(s)is/are inserted into the molded insulator and over the insertioninstrument and wherein the insertion instrument is then used to insertboth the one continuous formed loop of conductive material and themolded insulator into the stator core.
 5. The method of claim 4, furthercomprising the step of: forming circumferential flanges on the moldedinsulator.
 6. The method of claim 5, further comprising the step of:forming protrusions inside the molded insulator that assist in holdingthe conductive coil in place.
 7. The method of claim 1, furthercomprising the step of: installing a rotor having at least two polesinside the stator core.
 8. The method of claim 1, further comprising thestep of: forming an even number of poles based on the shape of theformed coil.
 9. The method of claim 1, further comprising the step of:providing at least one blade on an outer portion of the insertioninstrument.
 10. The method of claim 1, further comprising the step of:providing at least one hook on the insertion instrument that is designedto contact and hold a portion of the conductive coil.
 11. The methodclaim 10, further comprising the step of: forming a recess in theinsertion instrument such that the at least one hook can be retractedinto the insertion instrument.
 12. The method of claim 1, furthercomprising the step of: bonding the conductive material with anadhesive.
 13. The method of claim 1, further comprising the step of:supporting the at least one moveable end turn forming tool with anupstanding column having a slanted forming contour.
 14. The method ofclaim 13, further comprising the step of: retracting the at least oneend turn forming tool into a recess in the upstanding column.
 15. Themethod of claim 14, further comprising the step of: spring-biasing theat least one moveable end turn forming tool to an extended position. 16.The method of claim 1, further comprising the step of: forming a convexouter side on the first and second end turn forms.
 17. The method ofclaim 1, further comprising the step of: dipping the stator core into afluidized bed of powder and curing the powder on the stator core.